Oven structure



April 29, 1947. W,v H, HUDSON f 2,419,643

OVEN STRUCTURE Filed oct. 2, 1944 5 Sheets-Shee l April 29, 1947. w. H. HUDSON OVEN STRUCTURE Filed oct. 2. 1944 3 Sheets-Sheet 2 f/ l 7). ZT 1f "r INVENTOR. W///am H. Hua/son April 29, 1947.

w. H. HUDSON 2,419,643

OVEN STRUCTURE Filed Oct. 2, 1944' vSheets-Sheet 3 Patented pr. Z9, 1947 .UNITED angels STATES PATENT OFFICE James W. Swenson, Detroit, Mich.

Application October 2, 1944, Serial No. 556,870

6 Claims.

This invention relates to heat treating ovens and has to do particularly to ovens of the type for heat treating work pieces by subjecting the work pieces to infra-red rays.

Work pieces may be subjected to infra-red ray heating treatments for a variety of reasons. Foremost among these reasons is that of drying or baking coatings, such as various kinds of lacquers or paints or the like. Various installations and various sorts of work pieces require different heat treating functions. Moreover, the particular coating which is dried or baked is a factor which influences the extent of the time of the heat treatment and the temperature of the treatment. Also, work pieces of dierent sizes and shapes, and work pieces comprised of varying metals and mass require different types of heat treatment, particularly from the standpoint of the power input, the length of time, and the temperature attained.

Among the objects of the present invention is to provide an oven structure comprised essentially of standardized elements to the end that a .complete oven unit may be formed of standardized parts and any given installation may be provided with the desired or correct number ci oven units to meet the overall necessities of that installation. Moreover, the invention contemplates an oven structure admirably adapted for use in conjunction with a conveyor system so that the work pieces may be passed through the oven While on the production line.

While it is essential to provide a hot Zone for the work pieces, it is desirable, and even necessary in many cases, to maintain the electrical wiring system and the sockets for the lamps in a relatively cool condition, but this presents a problem due to the close proximity of the lamp bases and the wiring system to the hot Zone. Accordingly, an object of the invention is to provide an arrangement for the maintenance of a hot Zone and a relatively cool area in proximity to each other. To this end, an oven is provided which is of such a structure as to take advantage of the natural convection currents for cooling purposes, but which at the same time can be, if desired, equipped with suitable blower means for increasing the movement of cooling air. A factor in this phase of the invention is that of conning the rays efliciently in the hot zone, f

and temperature more than some other metals such, for example, as stainless steel; this may be due partially to its reiiecting capacity and partially to its molecular structure. The aluminum reflecting sheathing, accordingly, constitutes an eflicient partition between the hot zone for work pieces and the adjacent zone or area for the wiring system, lamp bases and sockets, etc.

Other objects will become appreciated as the following detailed description follows, these including an arrangement which, while closed at its sides, can be quickly and easily opened for the servicing oi any of the oven parts, including the replacement of lamps, and the mounting of conduits for the wiring in a novel manner so that a minimum number of mechanical elements are required and so that the conduits may be quickly and easily opened.

Fig. 1 is a side elevational view illustrating an oven structure made in accordance with the invention.

Fig. 2 is an enlarged. cross sectional view taken substantially on line 2--2 of Fig. 1.

Fig. 3 is a plan view of one of the reflecting panels.

Fig. 4 is a perspective view of a single unit oven showing the same without any Ventilating means other than natural convection currents.

Fig. 5 is a sectional view showing the arrangement for mounting the enclosing side panels.

Fig. 6 is a detailed View looking at Fig. 5 in a direction ci the arrows 6 6.

Fig. 7 is a detailed view illustrating the mounting of one ci the conduits.

Fig. 8 is a sectional view taken substantially on line 8 8 of Fig. 7.

Fig. 9 is a sectional view similar to Fig. 8 but taken through conduit at the location of a lamp socket.

In the general elevational View of Fig. 1, the complete oven structure is comprised of a number of oven units, each of which are of standardized construction. Assuming that the work pieces are to travel through the oven in a direction from the left to the right, the first oven unit is generally illustrated at l, and the second oven unit at 2. These two units may be of substantially identical construction and are placed end to end and secured together. The middle sections of the oven may comprise oven units 3 and 4. These units are larger than the units i and 2 and have a greater spacing between the lamps, as illustrated, but are of like construction and placed end to end. The opposite end of the oven may have one or more oven units corresponding to the units l and 2 and one of which is shown at 5. The inlet and the outlet ends of the oven may be provided with heat foyers 6 and 'l and the entire oven structure may be mounted upon suitable legs 8. In accordance with the desires or necessities of the work to be performed, the oven may be equipped with means for setting up a draft of air therethrough, and as shown the central units S and 4 are provided on top with a suitable shrouding 9 and a fan or blower i9 driven by a pulley l l, the fan or blower being connected to the shrouding by a conduit I2. A suitable air control damper is illustrated at i3. The blower may be employed to move air upwardly through the oven and. the same may be discharged, through pipe M.

The unit structure is shown in Figs. 2 and 4 and is comprised of vertical frame pieces 20 connected by horizontal frame members 2l. These frame members are preferably of angle iron as shown. Horizontally extending frame membe s, as at 22, connect the end frame structure provided by the members Eil and 2l. These frame members may and preferably are welded together and thus form a box-like frame structure. Where the oven is to be employed with a conveyor system, a section of a. conveyor rail is mounted on the upper cross members 2l. This rail section is to correspond to the rail used in the conveyor system and is here shown as an I beam Thus, the oven unit and its conveyor rail section are assembled together.

At this point, the description diverges from the oven to cover the diagrammatic illustration of the work piece moving th 'ough the oven on a conveyor. A suitable trolley 26 with rollers 21 operates on the rail and a suitable work piece holding device illustrated at 23 grips and holds the work piece suspended, as shown at 29.

The supporting structural elements within the frame is of open or skeleton construction and comprises number of brackets 3D preferably welded to the frame parts 2G and projecting inwardly. The number of brackets employed may depend upon the size of the oven. Also, where the oven is formed so that rays are directed onto the work pieces from the top and the bottom, brackets 3i are welded to the horizontal end pieces 2l.

Supporting members 32 are carried by the brackets 38. these parts being preferably welded together, These members are welded to the brackets 39 in an intermediate portion thereof, and where the members 32 are shaped, as shown in Fig. 2, the ends thereof may be welded to the cross frame members 2l. The opposite members 32 are identical and may advantageously be of stra-p or flat form and there is preferably a pair of these strap members adjacent each end of the oven unit.

Mounted on the inner ends of the brackets 38, preferably by means of welding, are other supporting elements. preferably in the torni of metal straps or strips There is an opposed pair of elements 33 adjacent each end of the oven unit, and these supporting elements are for carrying the reflector panels. One or" such panels is shown in Fig, 3, and it comprises a sheet of rolled rnetal` preferably aluminum, as shown at 35, provided with a number of apertures therethrough for accommodating the lamps, the apertures 'being shown at 35. The ends of the panels are provided with apertures for the reception of screws passing therethrough and threaded into the supporting elements 33, as shown at 3l. The longitudinal edges of the panels are turned back to form reinforcing flanges 33 to thus give the panels added strength and a finished edge appearance on the interior of the heat zone. These panels, for each oven unit, are of the same length and extend from end to end of the unit but may be of varying width, as shown in Fig, 2, depending upon the lamp arrangement. For example, the upper and lower panels 35 are arranged to accommodate one row of lamps and are narrower than the vertical panels which are arranged to accommodate two rows of lamps, When the panels are disposed as shown in Fig. 2, they define the hot zone or oven compartment and separate the hot zone from the area to the rear of the panels.

The wiring system and the sockets for the incandescent lamps are supported largely by the elements 22. rThe lamps are shown at 40 and their tips or head portions project through the openings in the reflecting panels. The openings are of such a size as to provide a working clearance for the bulbs, Mounted upon the elet 32 are conduits for electrical conductors, gcnerallv illustrated at 4l. These conduits are of channel form, preferably rectangular in cross section. The bottom portions of the channels are mounted agains the supporting elements 32, as shown in Figs. and 8, by means of bolts 42. The he the bolts are on the inner side of the elements and a nut 43 is turned down tight to hold the channels in position. Each channel is closed at its open side by a cover 44. The flanges, as at 45, fit over the sides of the conduit. The bolt 42 has a length such as to extend through an opening in the cover and the cover is held assembled by a winged nut 45. The bottom of the channels lll carry the sockets for the lamps, shown at 59, and the electrical conductors for the lamps are disposed in the conduit, as shown at 5l, and connected in a suitable manner to each of the sockets. Accordingly, as will be observed by reference to Fig. 2, there is a conduit for each horizontal row of lamps and which encloses the conductorsY and supports the sockets.

rhere is preferably om3 additional conduit on each side of the oven as shown at 52. These cond its carry the main conducting lines which extend lengthwise of the unit and which connect to the conductors in the conduits having the lamp sockets by suitable feeders 53. The feeders 53 are preferably taken oi the conduit 52 at various locations along the length of the oven in order to simplify the construction and keep the feeders d. As shown in Fig. 2, the main control switch is housed in a switch box 54. A suitable conduit, which is preferably ilexible, as shown at il carries conductors for connecting one switch with the wires in conduit 52 on one side of the oven while a conduit 55 carries conductors for ccnnectin,Cv into the conduit on the opposite side of the oven. The controlling switch box may be located in any convenient position. As shown in 1, the two switch boxes are located adjacent s .h other and one may be used for one oven unit the other may be used for an adjoining oven unit. A similar arrangement is shown in 1, and by cutting out one or more oven units the effective length of the heat zone may be varied to meet varying conditions or varying classes of work.

rhe sides of the oven units are closed by panels 5S and these panels are mounted so that they be readily and quickly removed. A structure for accomplishing this is shown in Fig. 5. A suitable number ci small brackets 6l are welded to the upper rail 22 and Welded to each bracket is a nut 62. The panel 60 is provided with an opening for a screw 63 arranged to be threaded into the nut. The upper edge of the panel is preferably folded back upon itself as shown at 64, to provide a smooth edge. Along the lower edge of each panel are a number of clips 65 welded thereto and shaped to fit over the edge of the lower rail 22. The lower edge of the panel may also be folded back on itself, as shown at 66, to provide a smooth edge. As shown in Fig. 1 and Fig. 4, there are three points of attachment along the upper rail but any suitable number will do and to remove a panel the screws 63 are removed. Then the upper edge of the panel may be swung outwardly a little bit and then lifted to disengage the clips 65 from the lower rail. The replacement of the panels is just the reverse. The panels may be cut away to clear the switch boxes.

In the use of the oven, the work passes therethrough on a suitable conveyor as illustrated. Where it is desired to bring the temperature of the work up rapidly, oven units I and 2 may be employed where the lamps are closely grouped together. Units such as 3 and 4 may be employed after the work has reached the desired temperature and it is desired only t0 maintain the temperature. The rays emitted from the lamps are directed onto the work and, thus, the work is heated by the generation of heat Within the material of the work itself. Some rays, of course, miss the work piece and other rays are reflected and thus strike the reflector shields. These rays are reflected back into the heat zone so that the energy is not lost. Some of the reilected rays may result in increasing the temperature in the zone while others may strike the work piece and aid in the heating of the work piece in itself. The aluminum reecting panels efficiently reiiect the rays and, due to the nature of the aluminum, the reector sheets remain relatively cool. This maintains a cool condition in the area or passages between the reilectors and the side panels and it is in this zone, as will be seen, that the conduits, conductors and lamp bases are located. Where the oven is used without any means for causing a forced draft arrangement, natural convection currents move upwardly through the passages between the reflecting panels and the side panels thus aiding in keeping the exterior areas cool. The top and bottom of such an oven unit may be left open as shown in Figs. 2 and 4. One or more units may be used with the forced draft arrangement as shown in Fig. l. Indeed, where a single unit is used, it may be equipped with a forced draft arrangement. The forced draft arrangement also draws air from the heat zone and thus removes vapcrs from the drying coatings. In some instances, the normal convection currents will suilice for this purpose.

The servicing of the oven may be done entirely from the outside and without requiring a workman to get into the heat zone in one way or another. The lamps may be replaced by removing the side panels and reaching in and unscrewing a lamp from its socket and then installing a new one. The clearance in the openings 36 permit a lamp to pass therethrough. Any time it is necessary to have access to the wiring, the cover 44 of any one of the conduits can be quickly removed by the removal of the winged nuts 45.

When an oven is to be designed to perform a particular class of work, one or more of the oven units may be put together in end to end relationship to provide the desired capacity and timing arrangement. By timing, we mean the time it takes the work to pass through the oven considering the rate of travel of the conveyor. The ultimate oven construction may comprise one or more units, such as the relatively long units 3 and 4, or one or more units, such as the relatively short units I and 2 or any one combination of these. And yet the oven units are standardized and constructed from standardized structural elements. The shape of the oven or hot zone is, of course, subject to variation, depending upon the work to be handled. As shown in Fig. 2, there are lamps for directing rays upon the top of the work and upwardly toward the bottom of the work. In some cases, the work may not require lamps so arranged. Other cases may require a diierent arrangement or angle.

I claim:

l. An oven structure for heat treating work pieces by infra-red radiation which comprises, a frame structure including spaced end portions having vertical frame members and cross frame members and lengthwise extending horizontal frame members connecting the end portions, a plurality of brackets secured to the end frame portions and extending inwardly of the frame, supporting members carried by the brackets at their intermediate portions, conduits for electrical conductors mounted on the supporting members and extending from end to end of the frame structure, so-me of said conduits having sockets therein for the reception of lamps constituting infra-red radiation sources, other supporting members carried substantially at the ends ci the brackets, sheet metal reector panels carried by the said other supports, said reector panels having openings therein for the lamps, the spacing between the supporting members being such that the envelopes of the lamps project partially through the openings, said reflector panels defining and partially surrounding a heat zone for work pieces.

2. An oven structure for heat treating work pieces by infra-red radiation which comprises, a frame structure including spaced end portions having vertical frame members and cross frame members and lengthwise extending horizontal 'frame members connecting the end portions, a

plurality of brackets secured to the end frame portions and extending inwardly of the frame, supporting members carried by the brackets at their intermediate portions, conduits for electrical conductors mounted on the supporting members and extending from end to end of the frame structure, some of said conduits having sockets therein for the reception of lamps constituting infra-red radiation sources, other supporting members carried substantially at the ends of the brackets, sheet aluminum reflector panels carried by the said other supports, said reector panels having openings therein for the lamps, the spacing between the supporting members being such that the envelopes of the lamps project partially through the openings, said reflector panels deningr and partially surrounding a heat zone for work pieces.

3. An oven structure for heat treating work pieces by infra-red radiation which comprises, a frame structure including spaced end portions having vertical frame members and cross frame members and lengthwise extending horizontal frame members connecting the end portions, a plurality of brackets secured to the end frame portions and extending inwardly of the frame,

supporting members carried by the brackets at their` intermediate portions, conduits for electrical conductors mounted on the supporting members and extending from end to end of the frame structure, some of said conduits having sockets therein for the reception or lamps constituting infra-red radiation sources, other supporting members carried substantially at the ends oi the brackets, sheet metal reiiector panels carried by the said other supports, said reflector panels having openings therein for the lamps, the spacing between the supporting members being such that the envelopes of the lamps project partiallv through the openings, said reflector panels defining and partially surrounding a heat Zone for work pieces, and a conveyor rail permanently mounted to the top cross frame members and adapted to support conveyor means for holding work pieces whereby the oven structure is adapted to be mounted in a section of a conveyor system.

4. An oven structure for heat treating work pieces by infra-red radiation which comprises, a frame structure including spaced end portions having vertical frame members and cross frame members and lengthwise extending horizontal frame members connecting the end portions, a plurality of brackets secured to the end frame portions and extending inwardly of the frame, supporting members carried by the brackets at their intermediate portions, conduits for electrical conductors mounted on the supporting members and extending from end to end of the frame structure, some of said conduits having sockets therein for the reception or lamps constituting infra-red radiation sources, other supporting members ca ried substantially at the ends oi the brackets, sheet metal reector panels carried by the said other supports, said reflector panels having openings therein for the lamps, the spacing between the supporting members being such that the envelopes of the lamps project partially through the openings, said reflector panels defining and partially surrounding a heat zone for work pieces, side panels for closing the sides oi the oven and means detachably holding the side panels in place whereby the same may be removed for access to the electrical conduits and lamps.

5. An oven structure for heat treating work pieces by infra-red radiation which comprises, two end. frame portions, horizontal frame members connecting the portions, each end portion comprising vertical and cross frame members, brackets secured to the frame members and extending inwardly, two supporting members oppositely positioned and extending substantially from top to bottom o the end frame portions, said supporting members being carried by the brackets, two other supporting members carried by the brackets, a plurality of sheet metal panels, each formed with a plurality of openings therein and each secured to one of the second named supporting elements at each end frame portion, said panels being disposed edge to edge and delining a heat zone therebetween, a plurality of conduits for electrical conductors extending from end to end of the oven and carried by the rst named supporting members, said conduits having sockets therein, electrical lamps located in the sockets and projecting partially through the openings in the panels for the radiation of rays onto work pieces in the heat zone, removable side panels, side panels and the reflecting panels defining air passages therebetween in which is located the conduits and the lamp sockets, the oven structure being substantially open at tcp and bottom for the passage of convection currents therethrough.

6. An oven structure ior heat treating work pieces by infra-red radiation which comprises, two end frame portions, horizontal frame members connecting the portions, each end portion comprising vertical and cross frame members, brackets secured to the frame members and extending inw rdly, two supporting members oppositely positioned and extending substantially from top to bottom of the end frame portions, said supportingy members being carried by the brackets. two other supporting members carried by the brackets, a plurality of sheet metal panels, each formed with a plurality of openings therein and each secured to one of the second named supporting elements at each end frame portion,

' anels being disposed edge to edge and dei e a heat zone therebetween, a plurality of conduits for electrical conductors extending from end end of the oven and carried by the first named supporting members, said conduits having socket? therein, electrical lamps located in the socket nd projecting partially through the openings in the panels for the radiation of rays onto work pieces in the heat zone, removable side panels, the si le panels and the reecting panels defining air passages therebetween in which is located the conduits and the lamp sockets, the oven structure being substantially open at top and bottom for the passage of convection currents therethrough, and a conveyor rail permanently mounted on the upper cross members of the frame structure for the conveying or work pieces through the heat zone.

WVM. H. HUDSON,

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,048,777 Brown July 28, 1936 2,263,865 Barber Nov. 25, 1941 2,347,407 Goodwin et al Apr. 25, 1944 

